Unfortunately, due to the great number of times those lists overlapped, the two decide that money does buy happiness (or, money buys cognitive dissonance, which is more likely in my opinion).

More interesting, I thought, were the items that appeared most often on one list, but not the other. Two that appeared on the "most expensive" list frequently, but not so much on the "happiness" list: cars (including insurance, gas and maintenance) and wedding ceremonies.

On the other end of the spectrum, appearing far more often on the "happiness" list and not on the "most expensive" list were bicycles (of all kinds, from commuter bikes to mountain bikes) and meals shared with friends, from dinner parties to potlucks.

Would that I could go back to the 25-year-old me and tell her that a fancy car and an expensive wedding wouldn't make her happy. Instead, 10 years later, she'd be delirious over a bicycle-built-for-four and a potluck birthday party for a toddler. Do you think she would listen?

And weddings! The average American couple spends $20,398 for their wedding (and that's 50% more than budgeted), not including engagement ring or honeymoon. The average American potluck equals the cost of groceries already in your fridge.

These seem to be easy places to avoid financial mistakes; it's hard, though, to avoid them from the age-25 perspective. Learn from me, young Walletpoppers.

However, there are a couple of other things you can feel good about paying for: camping gear, books and a really good mattress. Sleep is for the blissful, especially when it's under the stars and after a good book. Ahhh...